The present invention relates to a device for unloading X-ray film cassettes of the type in which a cassette to be unloaded is received in a compartment and further comprising means for the insertion and discharging the cassettes, means for a light tight closing of the compartment, a device for opening the lid or cover plate of the cassette, a blower which includes at least one nozzle positioned between the housing and the lid of the cassette for separating a film to be removed from the cassette, means to remove the film from the cassette and an electric or electronic control device by means of which all the means of the device are controlled.
The device of the foregoing type is disclosed, for example in U.S. Pat. No. 3,828,195. The cassette to be emptied is inclined downwardly in the direction of the film removal and, must be open to allow the film to be moved to the transport rollers due to inclination of the cassette. Thereby with an unfavorable air ratio, the film would neither hang on the cassette nor be guided from the cassette and the air stream before the leading side of the cassette would be directed upwardly and the film would be chipped off.
A second similar device for unloading film cassettes for cassettes with a forward-side closable film insertion and a film removal slot has been disclosed in DE-GMS 84 34 977. The cassette in this device is directed with its slot for unloading the films vertically downwardly, and the film being removed from the cassette is gravity-moved away from the cassette. To hold the film on the inner surface of the cassette the air blow is directed against the slot.
Cassette unloaders in which the cassette being unloaded is positioned horizontally and has a liftable or pivotable lid have a specific tacking effect between the cassette and the film. The film normally sticks to the lid or the lid-side reinforcement foil, and this normally pushes the film upwardly against the force of gravity. If such tacking effect is not sufficient and the film drops back onto the bottom of the cassette the sucker which serves to remove the film from the cassette will engage the bottom-side reinforcement foil rather than the film being removed. This causes, with very fast-operated unloaders, unexpected function disturbances which can lead to the damage of the illuminated film and the cassette itself. To avoid this tacking effect various means have been proposed, for example suction cups on the bottom of the cassette as disclosed in DE-PS 35 37 549. The upper edges of such suction cups have been often used up in the process and therefore did not fulfill their function.